Examine source code of Humble Steam Check

{
  "manifest_version": 3,
  "name": "Humble Steam Check",
  "version": "0.2.2",
  "description": "Shows which Humble Bundle games are already in your Steam library.",
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "https://api.steampowered.com/*",
    "https://store.steampowered.com/*",
    "https://www.humblebundle.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.humblebundle.com/*"
      ],
      "js": [
        "matcher.js",
        "content.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "humble-steam-check@deco.sh",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}